Joseph Ferano
831cab9fb2
Five fixes off the independent review, plus the author's u8 ruling.
x86 parity: the bad-index block always ran x86 (it is flan dev's
default) and now says so with an explicit --x86; the condition render
gets an assertion under the x86 backend too, beside the LLVM one, and
a user error is pinned as carrying no site on both.
ArithError's layout is now pinned: {i32 op; i64 lhs, rhs} in C against
the prelude's defstruct, read field by field through the break loop's
render, driven from the editor through a divide under a restart-case.
That also covers condition and site on LLVM.
Three refusals that were wrong: trap_site tested the prefix "err"
and so ate any site whose path began with those letters; source_line
let Sys_error from input_line escape and take the whole break reply
with it, leaking the handle; and a condition with no fields was
reported as a name no struct has. The daemon now sends its own field
count and the buffer tells the two empties apart.
Nits taken: an over-long site is dropped rather than silently
truncated into a plausible one; the caret pads with the source line's
own tabs; the headline says when it has cut the field list;
flan-cnr-layout is live again as the single spelling of that request
rather than dead beside an inlined copy.
And the ruling: a u8 renders as 97 (\a) where a person is inspecting
and stays 97 where the program is printing.
830 lines
41 KiB
EmacsLisp
830 lines
41 KiB
EmacsLisp
;;; flan-cnr.el --- What a stopped program is offering -*- lexical-binding: t; -*-
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;; Author: Joseph Ferano <joseph@ferano.io>
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;; Version: 0.1.0
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;; Package-Requires: ((emacs "29.1"))
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;; Keywords: languages, lisp, tools
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;; The headers above are what make this directory installable. M-x
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;; package-install-file on it reads them, and a file with no Version: is not a
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;; package as far as package.el is concerned -- until now the client was
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;; reachable only by adding it to load-path by hand, which is a thing to
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;; explain to every person who wants to try it.
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;;
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;; 29.1 is the floor because it is the oldest Emacs any of this has been run
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;; against, not because some function here is known to need it. dape, which
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;; flan-dape drives, asks for 29.1 as well and is a soft dependency: it is
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;; reached through declare-function, so the rest of the client loads and works
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;; without it and it is deliberately not listed above. The compiler this talks
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;; to is not an Emacs package and cannot be listed here either -- emacs/MANUAL.md
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;; says what has to be on PATH.
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;; `C-c C-b' is a `completing-read' over restart names. That is the whole UI
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;; for the one moment the dev loop exists to make survivable, and it is thin in
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;; a way that is worth being specific about: it shows the names and nothing
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;; else — not the condition's fields, not where the error was, not what the
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;; frame between here and the restart was doing — and it will happily let you
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;; choose a name that cannot be invoked. This is the buffer that replaces it.
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;;
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;; Two sources, and they answer different questions.
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;;
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;; **SBCL** answers *what to put first*. `invoke-debugger' prints the
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;; condition, then `show-restarts', and stops. The backtrace is a command you
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;; type, not something it shows you. That ordering is a claim: the restarts
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;; are the decision in front of you and the stack is the explanation for it,
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;; and a debugger that opens with forty frames has buried the decision under
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;; the explanation. So: condition, restarts, then the stack, and the stack's
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;; locals folded away until asked for.
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;;
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;; `show-restarts' also numbers them and brackets the name — and omits the
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;; bracket on a name already used further in. That device is not decoration.
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;; A restart *typed by name* resolves to the innermost frame offering it, so a
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;; second frame offering `retry' is real, is on the list, and cannot be named
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;; from a prompt — spec-conditions.md §4, and `flan_find_restart' in the
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;; runtime. Today's `completing-read' hides it: the list has `retry' twice,
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;; picking either sends the string "retry", and the inner one runs. Here
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;; every choice goes out by *number* (`restart-at', with the name as a
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;; receipt), so a shadowed entry is drawn without its bracket and is still
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;; takeable — the bracket says only what a typed name would reach.
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;;
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;; **CIDER's stacktrace buffer** answers *how it should behave*: frames that
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;; expand in place, TAB to fold, everything reachable from the keyboard,
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;; `q' to go. What was not taken from it is the cause chain — CIDER walks
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;; `ex-cause' because a JVM exception wraps another one, and a Flan condition
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;; wraps nothing — and its filters, which exist because a JVM backtrace is
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;; mostly frames nobody wrote.
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;;
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;; Everything this buffer cannot fill in is drawn as a section that says so, by
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;; name, with what it would take. A missing section is indistinguishable from
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;; a section that happened to be empty, and only one of those is a fact about
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;; the program.
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;;; Code:
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(require 'seq)
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(require 'subr-x)
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(declare-function flan--request "flan" (form))
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(declare-function flan-inspect "flan-inspect" (expr))
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(declare-function flan-inspect-slot "flan-inspect" (frame slot name))
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(defgroup flan-cnr nil
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"The conditions and restarts buffer."
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:prefix "flan-cnr-"
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:group 'flan)
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(defcustom flan-cnr-buffer "*flan-conditions*"
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"Where the break buffer draws."
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:type 'string)
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(defvar flan-cnr-request-function #'flan--request
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"How this buffer reaches the daemon.
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One plist in, the reply plist out. A variable so the renderers can be driven
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from fixtures, and so `flan.el' is named in one place.")
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;;; What is not available, and why
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;; Said in one table rather than at each use, so a section's reason is
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;; revisable in one place. One short sentence each: these print in the
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;; buffer, and the buffer is not the place for design notes.
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(defconst flan-cnr-unavailable
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'((layout
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. "no struct has this name; a trap's name has no fields behind it")
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(stack
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. "the program is running; ask again once it stops")
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(locals
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. "this frame has no named locals")
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(globals
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. "no frame on this stack reads a global; its state is all in its locals"))
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"Why a section of this buffer is empty, by name.")
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(defun flan-cnr--why (key)
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(or (cdr (assq key flan-cnr-unavailable)) "not implemented"))
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;;; Restarts, and which of them can actually be chosen
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(defun flan-cnr-annotate-restarts (names)
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"Turn NAMES — innermost first — into what the buffer draws.
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Each entry is (INDEX NAME SHADOWED-BY), where SHADOWED-BY is the index of the
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earlier entry that owns the name, or nil.
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This is §4's walk, computed here because it can be: `restart NAME' resolves
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through `flan_find_restart', which returns the first frame whose hash matches,
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so a name's second appearance is unreachable through the only verb there is.
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Nothing new has to be asked of the program to know that — the order of the
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list already says it."
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(let ((seen nil) (i -1))
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(mapcar (lambda (name)
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(setq i (1+ i))
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(let ((owner (cdr (assoc name seen))))
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(unless owner (push (cons name i) seen))
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(list i name owner)))
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names)))
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;;; Drawing
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(defvar-local flan-cnr--state nil
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"The plist this buffer was last drawn from.")
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(defvar-local flan-cnr--open nil
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"Indices of the frames whose locals are showing.")
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(defun flan-cnr--unavailable (key)
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(propertize (concat " not available — " (flan-cnr--why key) "\n")
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'face 'font-lock-comment-face))
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(defun flan-cnr--section (title)
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(insert (propertize (format "--- %s\n" title) 'face 'font-lock-comment-face)))
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(defconst flan-cnr-breakpoint "Pause"
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"The condition `(pause)' signals.
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`lib/prelude.ml' writes it as an ordinary struct under a `restart-case', so
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nothing in the compiler knows a breakpoint from an error and this buffer is the
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first place that can tell the difference. Named here rather than spelled at
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its use, because it is a fact about the prelude.")
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(defun flan-cnr--headline-fields (fields)
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"The condition's own numbers, folded into the headline.
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FIELDS is the fields list; the result is \"low 9, high 9, length 4\" over the
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fields whose values arrived and are short enough to read inline, or nil.
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Generic on purpose: the fields are the condition's own, so BoundsError reads
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as its numbers and every other condition reads as its own."
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(let ((short (seq-filter (lambda (f)
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(and (nth 2 f) (<= (length (nth 2 f)) 24)
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(not (string-match-p "\n" (nth 2 f)))))
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fields)))
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(when short
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(concat (mapconcat (lambda (f) (format "%s %s" (nth 0 f) (nth 2 f)))
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(seq-take short 4) ", ")
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;; A headline is one line, so a wide condition is cut — and
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;; says it is, because a silently short list reads as the whole
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;; of what the condition carries. The section below has all of
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;; them.
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(when (> (length short) 4) ", …")))))
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(defun flan-cnr--site-line-col (site)
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"The (LINE . COL) a SITE string names, or nil."
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(when (and site (string-match ":\\([0-9]+\\):\\([0-9]+\\)\\'" site))
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(cons (string-to-number (match-string 1 site))
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(string-to-number (match-string 2 site)))))
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(defun flan-cnr--insert-site (state)
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"Where the expression that trapped is written, with the line and a caret.
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The frame lines below say where each call was; this is the only record of the
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indexing or the division itself, so it sits directly under the headline."
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(let ((site (plist-get state :site)))
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(when site
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(insert (propertize (format "at %s\n" site) 'face 'shadow))
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(let ((source (plist-get state :source))
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(lc (flan-cnr--site-line-col site)))
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(when (and source lc)
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(let* ((prefix (format "%4d| " (car lc)))
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(col (max 0 (1- (cdr lc))))
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;; The pad copies the source's own leading whitespace rather
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;; than assuming spaces: a tab-indented line puts the caret
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;; a tab-stop off under any other rule, and a caret that
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;; points at the wrong column is worse than none.
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(pad (concat (make-string (length prefix) ?\s)
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(mapconcat
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(lambda (ch) (if (eq ch ?\t) "\t" " "))
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(string-to-list (substring source 0
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(min col (length source))))
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""))))
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(insert "\n" (propertize prefix 'face 'shadow) source "\n")
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(insert pad (propertize "^" 'face 'error) "\n")))))))
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(defun flan-cnr--insert-condition (state)
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(let* ((name (or (plist-get state :condition) "a condition"))
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;; A breakpoint is a stop, not a failure. Everything underneath is
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;; identical — `(pause)' *is* `error' under a `restart-case', which is
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;; what a breakpoint is in a language that has conditions — so the
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;; only thing that can be wrong here is the word for it. Calling a
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;; breakpoint unhandled would be a small lie told at the top of the
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;; one buffer that exists to say what happened.
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(paused (equal name flan-cnr-breakpoint))
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(numbers (flan-cnr--headline-fields (plist-get state :fields))))
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(insert (propertize name 'face (if paused 'warning 'error)))
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(when numbers (insert " — " numbers))
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(insert "\n")
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(insert (propertize
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(if paused
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"stopped at (pause); nothing has been unwound\n"
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"unhandled; stopped where it erred, nothing unwound\n")
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'face 'shadow))
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(flan-cnr--insert-site state))
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(insert "\n")
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(flan-cnr--section "Condition fields:")
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;; The shape and the values are two answers. The shape — names and types —
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;; is the daemon's own, out of the build it holds; the values are read out
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;; of the stopped program by a thunk the daemon builds. So a field can be
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;; named and typed while its value is missing, and the row says why in one
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;; sentence rather than being left off.
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(let ((fields (plist-get state :fields))
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(why (plist-get state :fields-why)))
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(if (null fields)
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;; Three different empties, and only one of them is a refusal. A
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;; condition that *declares* no fields is an ordinary thing — Pause is
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;; one — and saying "no struct has this name" about it would be
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;; false. `:fields-empty' is the daemon's own count, so this end is
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;; not inferring it from a list that is also empty when the read
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;; failed.
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(insert (propertize
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(cond
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((plist-get state :fields-empty)
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" this condition has no fields\n")
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(t (concat " not available — "
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(or why (flan-cnr--why 'layout)) "\n")))
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'face 'font-lock-comment-face))
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(progn
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;; The section-wide reason, once, above the rows — repeating it per
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;; field was the noise the rewording pass was asked to cut.
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(when why
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(insert (propertize (concat " not read — " why "\n")
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'face 'font-lock-comment-face)))
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(let ((w (apply #'max 4 (mapcar (lambda (f) (length (nth 0 f))) fields)))
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(tw (apply #'max 4 (mapcar (lambda (f) (length (or (nth 1 f) ""))) fields))))
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(dolist (f fields)
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(let ((start (point))
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(name (nth 0 f)) (type (or (nth 1 f) "?")) (value (nth 2 f)))
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(insert (format " :%s%s %s%s " name
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(make-string (- w (length name)) ?\s)
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(propertize type 'face 'font-lock-type-face)
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(make-string (- tw (length type)) ?\s)))
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(insert (if value value
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;; A field-specific reason — no printer for its type —
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;; is that row's own; a bare "not read" defers to the
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;; sentence above.
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(propertize
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(if (nth 3 f) (concat "not read — " (nth 3 f))
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"not read")
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'face 'font-lock-comment-face))
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"\n")
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(add-text-properties start (point)
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(list 'flan-cnr-inspect nil
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'mouse-face 'highlight))))))))
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(insert "\n"))
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(defun flan-cnr--insert-restarts (state)
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(flan-cnr--section "Restarts (innermost first) — RET or a digit takes one:")
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(let* ((names (plist-get state :restarts))
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(rows (flan-cnr-annotate-restarts names)))
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(if (null rows)
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(insert (propertize
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" none are active. Nothing between the error and the top offered one; abort, or fix a body and reload\n"
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'face 'font-lock-comment-face))
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(let ((w (apply #'max 4 (mapcar (lambda (r) (length (nth 1 r))) rows))))
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(dolist (r rows)
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(let* ((i (nth 0 r)) (name (nth 1 r)) (owner (nth 2 r))
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(start (point)))
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;; SBCL's bracket: it is there when the name reaches this frame and
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;; gone when it does not. A shadowed entry is still takeable — the
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;; choice goes out by number, not by name — so the missing bracket
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;; says only that typing the name at a prompt would reach the
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;; inner one.
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(insert (format " %2d: %s%s%s " i
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(if owner " " "[")
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(propertize name 'face
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(if owner 'shadow 'font-lock-keyword-face))
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(if owner " " "]")))
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(insert (make-string (- w (length name)) ?\s))
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(when owner
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(insert (propertize
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(format "same name as %d; taken by its number" owner)
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'face 'shadow)))
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(insert "\n")
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(add-text-properties start (point)
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(list 'flan-cnr-restart name
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'flan-cnr-shadowed owner
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'flan-cnr-index i
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'mouse-face 'highlight))))))
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;; Last, and on the same list, because it is the same decision: what you
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;; pick when none of the restarts is the answer.
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(let ((start (point)))
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(insert (format " %2d: [%s] " (length rows)
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(propertize "abort" 'face 'error)))
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(insert (propertize "end the program here; the dev session ends with it\n"
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'face 'shadow))
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(add-text-properties start (point)
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(list 'flan-cnr-abort t 'mouse-face 'highlight))))
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(insert "\n"))
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(defun flan-cnr--insert-stack (state)
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(flan-cnr--section "Stack (innermost first) — TAB folds a frame's locals:")
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(let ((frames (plist-get state :stack)))
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(if (null frames)
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(insert (flan-cnr--unavailable 'stack))
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(let ((i -1))
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(dolist (fr frames)
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(setq i (1+ i))
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(let ((start (point))
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(open (memq i flan-cnr--open)))
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(insert (format " %2d: %s %s%s\n" i
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(if open "v" ">")
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(propertize (or (plist-get fr :fn) "?")
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'face 'font-lock-function-name-face)
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(if (plist-get fr :loc)
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(propertize (format " %s" (plist-get fr :loc))
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'face 'shadow)
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"")))
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(add-text-properties start (point)
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(list 'flan-cnr-frame i 'mouse-face 'highlight)))
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;; Collapsed by default. A stopped program has as many locals as it
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;; has frames, and all of them at once is the backtrace problem again
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;; one level down.
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(when (memq i flan-cnr--open)
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(let ((locals (plist-get fr :locals)))
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(dolist (r (plist-get fr :refused))
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(insert (format " %s%s\n"
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(if (string-empty-p (nth 0 r)) ""
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(propertize (format "%s: " (nth 0 r))
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'face 'shadow))
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(propertize (nth 1 r) 'face 'shadow))))
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(if (null locals)
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(unless (plist-get fr :refused)
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(insert (flan-cnr--unavailable 'locals)))
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(dolist (l locals)
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(let ((start (point)))
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(insert (format " %s %s = %s\n"
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(propertize (nth 1 l) 'face 'font-lock-type-face)
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(nth 0 l) (nth 2 l)))
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;; The slot's *index*, which is the fourth element the
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;; `locals\=' reply now puts on each line, and not its name.
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;; A name does not identify a slot: two slots of one frame
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;; can share one, and a refused slot is absent from this
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;; list, so the position in it is not an identifier
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;; either. Sending the name is precisely the old bug —
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;; the name was evaluated as an expression wherever the
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;; evaluator stood, which is the right frame only when
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;; this is the innermost one.
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(add-text-properties
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start (point)
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(list 'flan-cnr-inspect (list :slot i (nth 3 l) (nth 0 l))
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'mouse-face 'highlight)))))))))))
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(insert "\n"))
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(defun flan-cnr--insert-globals (state)
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"Draw the globals the stopped stack reaches.
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One section rather than a fold under each frame, and that is the design rather
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than a layout choice. A global is not part of a frame — it is program state
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the frame happened to touch — so nesting it under one implies an ownership that
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is not there, and repeats the name once per frame that reads it.
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What recovers the useful half of per-frame nesting is the annotation: each
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entry says which frames touch it, by the same index the stack section numbers
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them with. \"the whole chain is reading this\" and \"only the innermost is\"
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are different facts and they read differently here.
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The order is the daemon's, and it is by the innermost frame that touches each
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one: a deep stack makes the union large, and proximity to the error is what
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puts the likely culprit on top."
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(flan-cnr--section "Globals this stack reaches — innermost frame first:")
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(let ((globals (plist-get state :globals))
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(refused (plist-get state :globals-refused))
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(skipped (plist-get state :globals-skipped)))
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(if (and (null globals) (null refused) (null skipped))
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(insert (flan-cnr--unavailable 'globals))
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(let ((w (apply #'max 1 (mapcar (lambda (g) (length (nth 0 g))) globals))))
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(dolist (g globals)
|
|
(let ((start (point))
|
|
(frames (nth 3 g)))
|
|
(insert (format " %s%s %s = %s"
|
|
(nth 0 g)
|
|
(make-string (- w (length (nth 0 g))) ?\s)
|
|
(propertize (nth 1 g) 'face 'font-lock-type-face)
|
|
(nth 2 g)))
|
|
;; No frames at all should not be reachable — the daemon chooses
|
|
;; these *by* the frames that touch them — but "frame" followed by
|
|
;; nothing would be the one shape here that reads as a bug in the
|
|
;; program rather than in this line, so it says so instead.
|
|
(insert (propertize
|
|
(if (null frames) " (no frame recorded)\n"
|
|
(format " %s %s\n"
|
|
(if (cdr frames) "frames" "frame")
|
|
(mapconcat #'number-to-string frames ", ")))
|
|
'face 'shadow))
|
|
;; The same property the locals lines carry, so `i' reaches a
|
|
;; global exactly as it reaches a local: a global *is* an
|
|
;; expression in the source, which is what the inspector needs.
|
|
(add-text-properties start (point)
|
|
(list 'flan-cnr-inspect (list :expr (nth 0 g))
|
|
'mouse-face 'highlight)))))
|
|
(dolist (r refused)
|
|
(insert (format " %s%s\n"
|
|
(if (string-empty-p (nth 0 r)) ""
|
|
(propertize (format "%s: " (nth 0 r)) 'face 'shadow))
|
|
(propertize (nth 1 r) 'face 'shadow))))
|
|
;; A frame the daemon could not attribute means the union above is not
|
|
;; the whole union. Said, rather than left to look like a complete
|
|
;; answer with fewer entries in it.
|
|
(when skipped
|
|
(insert (propertize
|
|
" the union is incomplete; these frames could not be attributed:\n"
|
|
'face 'font-lock-warning-face))
|
|
(dolist (s skipped)
|
|
(insert (propertize (format " %s — %s\n" (nth 0 s) (nth 1 s))
|
|
'face 'shadow))))))
|
|
(insert "\n"))
|
|
|
|
(defun flan-cnr--render (state)
|
|
"Draw STATE, a plist, into the current buffer."
|
|
(let ((inhibit-read-only t))
|
|
(erase-buffer)
|
|
(setq flan-cnr--state state)
|
|
;; SBCL's order: what happened, what you can do about it, then why.
|
|
(flan-cnr--insert-condition state)
|
|
(flan-cnr--insert-restarts state)
|
|
(flan-cnr--insert-stack state)
|
|
;; After the stack, because it is scoped *by* the stack: the frame numbers
|
|
;; an entry is annotated with have to be on screen above it to read.
|
|
(flan-cnr--insert-globals state)
|
|
(insert (propertize
|
|
"RET/0-9 take a abort TAB fold a frame i inspect g refresh q quit\n"
|
|
'face 'shadow))
|
|
(goto-char (point-min))))
|
|
|
|
;;; Commands
|
|
|
|
(defun flan-cnr-take ()
|
|
"Take the restart on this line."
|
|
(interactive)
|
|
(cond
|
|
((get-text-property (point) 'flan-cnr-abort) (flan-cnr-abort))
|
|
((get-text-property (point) 'flan-cnr-restart)
|
|
(flan-cnr--invoke (get-text-property (point) 'flan-cnr-index)
|
|
(get-text-property (point) 'flan-cnr-restart)))
|
|
((get-text-property (point) 'flan-cnr-frame) (flan-cnr-toggle-frame))
|
|
(t (user-error "flan: nothing to take on this line"))))
|
|
|
|
(defun flan-cnr--invoke (index name)
|
|
"Take restart INDEX, named NAME.
|
|
By index, because the index is the identity — two frames can offer `retry'
|
|
and only one of them is the one on this line. The name rides along as a
|
|
receipt: the daemon checks it against what the program has at that index and
|
|
refuses if the two have drifted apart, so a stale buffer cannot take a
|
|
different restart than the one it showed."
|
|
(let ((r (funcall flan-cnr-request-function
|
|
(list :op "restart-at" :index index :name name))))
|
|
(if (equal (plist-get r :status) "ok")
|
|
;; Accepted, not resumed — the choice is validated against the stopped
|
|
;; stack and taken when that thread next comes round its loop. So the
|
|
;; buffer says so and goes, rather than redrawing a state that is about
|
|
;; to stop being true.
|
|
(progn (message "flan: %s — %s" name (or (plist-get r :note) "accepted"))
|
|
(quit-window))
|
|
(user-error "flan: %s" (or (plist-get r :message) "refused")))))
|
|
|
|
(defun flan-cnr-take-number (n)
|
|
"Take restart number N, as SBCL's debugger does."
|
|
(interactive (list (- last-command-event ?0)))
|
|
(save-excursion
|
|
(goto-char (point-min))
|
|
(let ((found nil))
|
|
(while (and (not found) (not (eobp)))
|
|
(when (and (equal n (get-text-property (point) 'flan-cnr-index))
|
|
(or (get-text-property (point) 'flan-cnr-restart)
|
|
(get-text-property (point) 'flan-cnr-shadowed)))
|
|
(setq found t))
|
|
(unless found (forward-line 1)))
|
|
(if found (flan-cnr-take)
|
|
;; The abort line's number is one past the last restart.
|
|
(let ((names (plist-get flan-cnr--state :restarts)))
|
|
(if (= n (length names)) (flan-cnr-abort)
|
|
(user-error "flan: there is no restart %d" n)))))))
|
|
|
|
(defun flan-cnr-abort ()
|
|
"Let the stopped program die where it stopped."
|
|
(interactive)
|
|
(let ((r (funcall flan-cnr-request-function '(:op "abort"))))
|
|
(if (equal (plist-get r :status) "ok")
|
|
(progn (message "flan: %s" (or (plist-get r :note) "aborted")) (quit-window))
|
|
(user-error "flan: %s" (or (plist-get r :message) "refused")))))
|
|
|
|
(defun flan-cnr-toggle-frame ()
|
|
"Show or hide this frame's locals."
|
|
(interactive)
|
|
(let ((i (get-text-property (point) 'flan-cnr-frame)))
|
|
(unless i (user-error "flan: point is not on a frame"))
|
|
(setq flan-cnr--open
|
|
(if (memq i flan-cnr--open) (delq i flan-cnr--open)
|
|
(cons i flan-cnr--open)))
|
|
;; Fetched on first open and then kept: a frame's locals cannot change
|
|
;; while the program is stopped, and re-asking on every fold would put a
|
|
;; round trip behind a keystroke that looks like pure redrawing.
|
|
;; Only when there is something to ask. The fixture tests render this
|
|
;; buffer from a literal state with no socket behind it and no `flan'
|
|
;; loaded, and folding a frame must stay a display operation there — the
|
|
;; renderer already draws a reason for a frame whose locals are nil, which
|
|
;; is the same degradation every other section of this buffer uses.
|
|
(when (and (memq i flan-cnr--open)
|
|
(functionp flan-cnr-request-function))
|
|
(let ((fr (nth i (plist-get flan-cnr--state :stack))))
|
|
(when (and fr (not (plist-get fr :fetched)))
|
|
(let ((answer (flan-cnr-locals i)))
|
|
(setcar (nthcdr i (plist-get flan-cnr--state :stack))
|
|
(plist-put (plist-put (plist-put fr :locals (nth 0 answer))
|
|
:refused (nth 1 answer))
|
|
:fetched t))))))
|
|
(let ((line (line-number-at-pos)))
|
|
(flan-cnr--render flan-cnr--state)
|
|
(goto-char (point-min))
|
|
(forward-line (1- line)))))
|
|
|
|
(defun flan-cnr-inspect ()
|
|
"Open the inspector on the thing at point.
|
|
|
|
A local and a global reach it by different roots, and that is the fix rather
|
|
than an inconsistency. A global is reached by *name*: the loaded thunk binds
|
|
to the program's own storage through the dynamic linker, so its name is an
|
|
expression that means the same thing wherever it is evaluated. A local is
|
|
not — it is storage in one frame, and its name evaluated anywhere else may
|
|
find a global, another binding of the same name, or nothing. So a local goes
|
|
in by frame and slot index, which is what the listing above it is already
|
|
drawn from."
|
|
(interactive)
|
|
(let ((root (get-text-property (point) 'flan-cnr-inspect)))
|
|
(unless root
|
|
;; Two different misses, and saying the wrong one sends someone looking
|
|
;; for a missing feature when they are one keystroke away. Being *on* a
|
|
;; frame is the common case — the frame line is what the eye lands on —
|
|
;; so name TAB rather than repeating why a local might be absent.
|
|
(user-error
|
|
(if (get-text-property (point) 'flan-cnr-frame)
|
|
"flan: this is the frame's own line; TAB opens it, then i on a local"
|
|
"flan: point is not on a local or a global — TAB opens a frame, i inspects a local in it or a global below")))
|
|
(require 'flan-inspect)
|
|
(pcase root
|
|
(`(:slot ,frame ,slot ,name) (flan-inspect-slot frame slot name))
|
|
(`(:expr ,expr) (flan-inspect expr))
|
|
(_ (user-error "flan: this line carries no root the inspector knows")))))
|
|
|
|
(defun flan-cnr-refresh ()
|
|
"Ask the program again what it is offering."
|
|
(interactive)
|
|
(flan-cnr-show))
|
|
|
|
(defun flan-cnr-next ()
|
|
"Move to the next line that does something."
|
|
(interactive)
|
|
(let ((p (point)))
|
|
(forward-line 1)
|
|
(while (and (not (eobp)) (not (flan-cnr--actionable-p (point))))
|
|
(forward-line 1))
|
|
(when (eobp) (goto-char p))))
|
|
|
|
(defun flan-cnr-previous ()
|
|
"Move to the previous line that does something."
|
|
(interactive)
|
|
(let ((p (point)))
|
|
(forward-line -1)
|
|
(while (and (not (bobp)) (not (flan-cnr--actionable-p (point))))
|
|
(forward-line -1))
|
|
(unless (flan-cnr--actionable-p (point)) (goto-char p))))
|
|
|
|
(defun flan-cnr--actionable-p (pos)
|
|
(or (get-text-property pos 'flan-cnr-restart)
|
|
(get-text-property pos 'flan-cnr-shadowed)
|
|
(get-text-property pos 'flan-cnr-abort)
|
|
(get-text-property pos 'flan-cnr-frame)
|
|
(get-text-property pos 'flan-cnr-inspect)))
|
|
|
|
(defun flan-cnr-tab ()
|
|
"Fold this frame, or move to the next actionable line.
|
|
|
|
TAB does two things because the buffer has two kinds of line and the section
|
|
header already promised the first one: on a frame, it opens or closes that
|
|
frame's locals; anywhere else, it moves. `f' still folds unconditionally, for
|
|
anyone who would rather TAB always moved."
|
|
(interactive)
|
|
(if (get-text-property (point) 'flan-cnr-frame)
|
|
(flan-cnr-toggle-frame)
|
|
(flan-cnr-next)))
|
|
|
|
(defvar flan-cnr-mode-map
|
|
(let ((map (make-sparse-keymap)))
|
|
(define-key map (kbd "RET") #'flan-cnr-take)
|
|
(define-key map [mouse-1] #'flan-cnr-take)
|
|
(define-key map (kbd "TAB") #'flan-cnr-tab)
|
|
(define-key map [backtab] #'flan-cnr-previous)
|
|
(define-key map "n" #'flan-cnr-next)
|
|
(define-key map "p" #'flan-cnr-previous)
|
|
(define-key map "f" #'flan-cnr-toggle-frame)
|
|
(define-key map "i" #'flan-cnr-inspect)
|
|
(define-key map "a" #'flan-cnr-abort)
|
|
(define-key map "g" #'flan-cnr-refresh)
|
|
(define-key map "q" #'quit-window)
|
|
;; Numbered, as SBCL's are, and for SBCL's reason: the names are not
|
|
;; unique, so the number is the only unambiguous handle a person has.
|
|
(dotimes (i 10)
|
|
(define-key map (kbd (number-to-string i)) #'flan-cnr-take-number))
|
|
map)
|
|
"Keys in `flan-cnr-mode'.")
|
|
|
|
(define-derived-mode flan-cnr-mode special-mode "flan-break"
|
|
"What a stopped Flan program is offering."
|
|
(setq buffer-read-only t))
|
|
|
|
(defun flan-cnr-state-from-reply (reply &optional fields stack globals)
|
|
"The buffer's state, out of a `break' REPLY.
|
|
FIELDS is what `flan-cnr-condition-fields' returned — rows of
|
|
(NAME TYPE VALUE), with VALUE nil where it could not be read, and the
|
|
one-sentence reason beside them — or the bare rows, which is how the
|
|
fixture-driven tests pass them.
|
|
|
|
GLOBALS is what `flan-cnr-globals' returned, or nil.
|
|
|
|
Everything this cannot fill in is left nil deliberately: the renderer draws a
|
|
section saying why rather than leaving one out, and a section that is absent
|
|
cannot be told from one that is empty.
|
|
|
|
Takes the layout rather than fetching it, so this stays a function from data to
|
|
data and the fixture-driven tests can drive it without a socket."
|
|
(list :condition (plist-get reply :condition)
|
|
:restarts (plist-get reply :restarts)
|
|
;; Where the expression that trapped is written, and that line's text.
|
|
;; `break' carries both when the stop has a site; a user (error ...)
|
|
;; has none, and then the headline simply has no line to point at.
|
|
:site (plist-get reply :site)
|
|
:source (plist-get reply :source)
|
|
;; FIELDS is either the rows themselves — the fixtures' shape — or
|
|
;; `flan-cnr-condition-fields''s plist of rows plus the one-sentence
|
|
;; reason the values half is missing.
|
|
:fields (if (keywordp (car-safe fields))
|
|
(plist-get fields :fields)
|
|
fields)
|
|
:fields-why (and (keywordp (car-safe fields)) (plist-get fields :why))
|
|
:fields-empty (and (keywordp (car-safe fields))
|
|
(plist-get fields :empty))
|
|
;; STACK is passed in rather than fetched, for the same reason FIELDS
|
|
;; is: this stays a function from data to data, so the fixture tests
|
|
;; drive it with no socket. Nil is still a legitimate answer — the
|
|
;; renderer draws the reason rather than leaving the section out.
|
|
:stack stack
|
|
:locals nil
|
|
;; Three keys rather than one nested structure: the renderer draws the
|
|
;; entries, the per-global refusals and the unattributable frames in
|
|
;; three different shapes, and a plist it can `plist-get' each of is
|
|
;; what keeps `flan-cnr--insert-globals' a function of its argument.
|
|
:globals (nth 0 globals)
|
|
:globals-refused (nth 1 globals)
|
|
:globals-skipped (nth 2 globals)))
|
|
|
|
(defun flan-cnr-layout (type)
|
|
"The fields of TYPE, as the renderer wants them, or nil.
|
|
`layout' is answered out of the daemon's own `Tast.structs' — it owns the
|
|
build — so this costs no round trip to the program and works while it is
|
|
stopped, which is the only moment this buffer exists in.
|
|
|
|
TYPE is the string `break' reported as `:condition', and that string is the
|
|
qualified struct name the compiler put into the error: `Emit' takes it from
|
|
`Types.Named', the agent holds it in `condition_name', and the daemon looks it
|
|
up by the same name. So it resolves without anything here knowing what package
|
|
it came from.
|
|
|
|
A refusal is not an error here: `:fields' nil means the section draws the
|
|
reason it is empty, which is the degradation the buffer is already built for,
|
|
and `:why' carries the daemon's own sentence for it — a bare name it will not
|
|
guess between two packages reads better than anything this end could invent.
|
|
|
|
Returns (:fields ROWS :why WHY), the shape `flan-cnr-condition-fields'
|
|
returns, so the two are interchangeable where the buffer takes either."
|
|
(let ((r (and type (not (string-empty-p type))
|
|
(funcall flan-cnr-request-function
|
|
(list :op "layout" :type type)))))
|
|
(if (equal (plist-get r :status) "ok")
|
|
(list :fields
|
|
(mapcar (lambda (f)
|
|
;; The value is nil: the shape of a condition is a
|
|
;; fact about the build, its contents are a fact about
|
|
;; the stopped frame, and this op only ever answers
|
|
;; the first.
|
|
(list (nth 0 f) (nth 1 f) nil))
|
|
(plist-get r :fields))
|
|
:why "the stop's value was not readable")
|
|
(list :fields nil :why (plist-get r :message)))))
|
|
|
|
(defun flan-cnr-condition-fields (type)
|
|
"The stopped condition's fields with their values, or what stands in.
|
|
Asks `condition' first — the daemon builds a thunk that renders the fields at
|
|
the pointer the break loop stashed — and falls back to `layout' when that is
|
|
refused, so the names and the types still show with one sentence saying why
|
|
the values do not. Returns (:fields ROWS :why WHY): ROWS are
|
|
(NAME TYPE VALUE [WHY]) with VALUE nil where it was not read, and WHY is the
|
|
section-wide reason, nil when the values arrived."
|
|
(let ((r (funcall flan-cnr-request-function '(:op "condition"))))
|
|
(if (equal (plist-get r :status) "ok")
|
|
(list :fields
|
|
(append
|
|
(mapcar (lambda (f) (list (nth 0 f) (nth 1 f) (nth 2 f)))
|
|
(plist-get r :fields))
|
|
;; A field the renderer refused — no printer for its type —
|
|
;; still shows, with its own reason in the value column.
|
|
(mapcar (lambda (f) (list (nth 0 f) nil nil (nth 1 f)))
|
|
(plist-get r :refused)))
|
|
:why nil
|
|
;; The build's own count. Zero means this condition declares no
|
|
;; fields, which is a fact about it and not a failure to read
|
|
;; one.
|
|
:empty (eql 0 (plist-get r :declared)))
|
|
;; The shape alone, through the one function that spells the `layout'
|
|
;; request. Its own reason is kept when it is the one that refused —
|
|
;; "not a qualified name" says more than anything about the values —
|
|
;; and the values' reason otherwise.
|
|
(let* ((why (plist-get r :message))
|
|
(fallback (flan-cnr-layout type)))
|
|
(list :fields (plist-get fallback :fields)
|
|
:why (if (plist-get fallback :fields)
|
|
(or why (plist-get fallback :why))
|
|
(or (plist-get fallback :why) why)))))))
|
|
|
|
(defun flan-cnr-backtrace ()
|
|
"The stopped program's frames, innermost first, as the renderer wants them.
|
|
|
|
Unlike `flan-cnr-layout', this *does* reach the program: the frame chain is the
|
|
shadow stack the dev build pushes, and only the stopped thread can read it. It
|
|
is taken from a snapshot made when the break was entered, for the same reason
|
|
the restart list is — a stack that is still moving cannot be numbered.
|
|
|
|
Frames are marked `program' or `eval'. An `eval' frame belongs to an
|
|
expression evaluated *inside* the break loop, sitting on top of the frames that
|
|
were there when it stopped; it is shown rather than hidden, because \"why is
|
|
there a frame I did not write\" is a fair question and silence is the wrong
|
|
answer to it.
|
|
|
|
Locals are left nil here and fetched per frame when one is opened. A stopped
|
|
program has as many sets of locals as it has frames, and rendering all of them
|
|
to draw one is the backtrace problem one level down."
|
|
(let ((r (funcall flan-cnr-request-function '(:op "backtrace"))))
|
|
(when (equal (plist-get r :status) "ok")
|
|
(mapcar (lambda (f)
|
|
(list :fn (nth 0 f) :loc (nth 1 f)
|
|
:kind (nth 2 f) :nslots (nth 3 f)
|
|
:locals nil :fetched nil))
|
|
(plist-get r :frames)))))
|
|
|
|
(defun flan-cnr-locals (frame)
|
|
"What FRAME's named locals hold, as (NAME TYPE VALUE) rows.
|
|
|
|
Returns two values in one list: the rows, and the refusals — a slot the daemon
|
|
declined to show, with the reason. The refusals are shown, not dropped: a
|
|
local that is missing because the compiler invented it and a local that is
|
|
missing because this is broken look identical if only one of them is drawn.
|
|
|
|
Nothing is copied out of the program. The daemon compiles a thunk that renders
|
|
the types it already knows at the addresses the program hands back, which is
|
|
why this works at all while the thread is stopped."
|
|
(let ((r (funcall flan-cnr-request-function (list :op "locals" :frame frame))))
|
|
(if (equal (plist-get r :status) "ok")
|
|
(list (plist-get r :locals) (plist-get r :refused))
|
|
(list nil (list (list "" (or (plist-get r :message) "refused")))))))
|
|
|
|
(defun flan-cnr-globals ()
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"The globals the stopped stack reaches: (ENTRIES REFUSED SKIPPED).
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ENTRIES are (NAME TYPE VALUE FRAMES) rows, ordered by the innermost frame that
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touches each one, with FRAMES the indices of every frame that does.
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Unlike the locals, this is fetched once for the whole buffer rather than per
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frame when one is opened, and that follows from what it is: a section scoped to
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the stack has one answer, and asking per frame would be asking the same
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question as many times as there are frames and then unioning the results here.
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REFUSED is a global the structural printer had no arm for, by name and with the
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reason. SKIPPED is a *frame* the daemon could not attribute — an expression's
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own frame, a lifted handler clause, or a body redefined since it was entered —
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which matters because it means the union is smaller than the real one. Both
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are drawn rather than dropped, for the reason the whole buffer is built on: a
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list that is missing something and a list that is complete look identical if
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nothing says which it is."
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(let ((r (funcall flan-cnr-request-function '(:op "globals"))))
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(when (equal (plist-get r :status) "ok")
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(list (plist-get r :globals)
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(plist-get r :refused)
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(plist-get r :skipped)))))
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;;;###autoload
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(defun flan-cnr-show ()
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"Show what the stopped program is offering, in a buffer.
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Refuses while the program is running, by name: there is no restart stack to
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walk from a running program."
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(interactive)
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(let ((r (funcall flan-cnr-request-function '(:op "break"))))
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(unless (equal (plist-get r :status) "ok")
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(user-error "flan: %s" (or (plist-get r :message) "refused")))
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(unless (plist-get r :stopped)
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(user-error "flan: the program is running; there is no restart stack to walk"))
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(let ((buf (get-buffer-create flan-cnr-buffer)))
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(with-current-buffer buf
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(unless (derived-mode-p 'flan-cnr-mode) (flan-cnr-mode))
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(flan-cnr--render
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(flan-cnr-state-from-reply r
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(flan-cnr-condition-fields
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(plist-get r :condition))
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(flan-cnr-backtrace)
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(flan-cnr-globals))))
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(pop-to-buffer buf)
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buf)))
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(provide 'flan-cnr)
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;;; flan-cnr.el ends here
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